Many sensory receptors are capable of detecting signals from more than one sensory channel. This study is designed to determine whether the macula lagena of the avian inner ear is a low-frequency auditory receptor as well as an organ for balance and postural control. Two objectives of this study are to clarify the acoustic role of the macula lagena and to uncover the mechanisms that permit these multiple sensory channels to be processed by one sense organ. The investigations make use of microsurgical techniques developed to access highly specific regions of inner-ear mechanoreceptors. With its slight modifications to the basic vertebrate-eye plan, the retina of the pigeon is capable of detecting both ultraviolet and linearly polarized light. The detailed studies of these sensory mechanisms in the avian eye should contribute to our understanding of vertebrate sensory receptor function, particularly of how small changes in retinal physiology can make large changes in the biophysical response properties of visual receptors. Avian visual physiology is being studied by both electroretinographic and behavioral methods.